Process of toughening manganese steel.



Patented Mafr. l2, 190|.l H. u; HlBBAo. PROCESS 0F TOUGHENING MANGANESESTEEL.

(Application tiled Aug. 6, 1897.)

IN VENTR Heummi KRD-- um @Y ATTORNEYS.

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HENRY D. I-IIBBARD, OF NORTH PLAINFIELD, NEW JERSEY.

PROCESS OF TOUGHENING MANGANESE STEEL.

SPECIFICATION forming part of Letters Patent No. 669,925, dated March12, 1901.

Application led August 6, 1897. Serial No. 647,312. (N0 Specimens.)

To all whom, it may concern;

Be it known that I, HENRY D. HIBBARD, a citizen of the United States ofAmerica,.re siding in North Plainfield, Somerset county, New Jersey,have invented certain Improvements in Toughening Manganese Steel, ofwhich the following is a specification.

My invent-ion consists of certain improvements in toughening castings orother articles of manganese steel, fully described hereinafter.

In order to give manganese-steel articles the best physical properties,it is essential that such articles be heated to a high degree and thenquickly cooled in a bath. If such articles have a considerablethickness-say over one inch-they are liable to be injured or rendereddefective by internal ruptures if they are heated quickly. Such internalrupture is due to strains caused by rapid, and

therefore irregular, heating, and is especiallyV marked in manganesesteel, because of its low heat-conducting power. A method heretoforeadopted of overcoming these difficulties has been to charge themanganesesteel articles into a cold furnace, which is then fired slowlyup to the proper degree of heat,w"here upon the articles are withdrawnand quickly plunged into a cooling-bath. This method carries with it theobjection that it is wasteful of fuel. It allows a given furnace to givebut a small output, and especially when work is pressing the furnace isapt not to be allowed to cool off sufficiently before a new charge isput in, and the castings or other articles of the new charge are liableto be dam aged accordingly. j

The objects of my invention are to avoid these objections, to provide amode of working which will permit of a continuous operation of thefurnace or furnaces, increase the output accordingly, save fuel, and yetinsure that gradual heating which is essential to the proper treatmentof manganese steel. I attain these objects by the mode of operationwhich I` will now describe.

I provide a long furnace (or two furnaces in series may be employed)with a horizontal or slightly-inclined hearth and with the fireplace orother heating means so arranged that one end can be heated to thehighest temordinary atmospheric temperature.

perature required for the process, while the temperature of the heatingchamber or chambers will be gradually less as the other end of thefurnace or furnaces is approached. At this cool end the temperatureshould be near By this means I establish in the heatingfurnace a seriesof what may be termed consecutive heating zones,having temperaturesincreasing gradually from a low predetermined ternperature which willnot injure the articles up to a high heat, and the temperature of eachzone is maintained at a practically7 uniform degree.

The articles to be treated are introduced or charged at or near the coolend of the furnace or furnaces and are slowly transferred toward the hotend by rolling, if of suitable shape, or by pushing or sliding or bytransfer from door to door or by equivalent means. When at the hot endof the furnace or furnaces the articles have reached the desiredtemperature, they are withdrawn and quickly plunged into a cooling-bathto complete the toughening operation.

I do not confine myself to any special construction of furnace orfurnaces for carrying out my invention; but in the accompanyingdrawingsI have illustrated one construction of furnace which may beused.

Figure l is a side elevation. Fig. 2 is a transverse vertical section onthe line 2 2, Fig. l; and Fig. 3 is a sectional plan on the line 3 3,Figs. l and 2.

A' is the long heating-chamber, having opposite ends ot a', closed bydoors, and at the sides a series of openings a2 CL3, of suitable size,closed by doors. At one end is the iireplace or other source of heat F,and at the same end, but on the opposite side of the furnace, is thechimney or outlet-flue C. This end of the heating-chamber is to beheated to the highest temperature required for the operation, while theopposite end of the chamber will be comparatively cool. Slidingpartitions P may be employed to aid in regulating the temperature indiiferent parts of the chamber. The manganese-steel articles areintroduced through the doorway a and as required are moved forwardsuccessively t0- Ward the hot end of the furnace by any suit- IOO ablemeans. Thus if the articles are cylindrical or of other shapes suitablefor rolling they may be rolled forward toward vthe hot end from time totime by means of ba-rs or other instruments introduced through the holesa2 a2.

If the articles are not thick, the operation may be shortened byintroducing them into the furnace at a point between the coldest andhottest ends, as through one of the doorways a3, where the degree ofheat is as great as experience has shown can be endured by the articlewithout injury. When heated to the required heat-say 1,700o Fahrenheitatthe hot end of the furnace, they are Withdrawn through the door a andplunged quickly into a cooling-bath.

It will be observed that a characteristic feature of my heating-furnaceis that there is a long part of the chamber through which the Iiames orproducts of combustion do not sweep on their way to the outlet orchimney, but through which the articles are fed toward the flames orproducts of combustion, the heatin which portion of said chamber beingthat due to radiation from the flames or products of com bustiou and thewalls of the furnace, such heat gradually diminishing in temperature inproportion to the distance from the furnace end of the chamber.

I claim as my invention- The mode herein described of toughe'ningmanganese-steel articles, said mode consisting in first, establishing,in a heating apparatus, a series of consecutive heating zones havingtemperatures increasing gradually from a 10W predetermined temperaturewhich will notinjure the articles to a high heat and maintaining thetemperature of each zone at a substantially uniform degree, thenintroducing the articles successively into the zone of lowesttemperature and moving them through the consecutive zones so as tosubject them to a gradually-increasing temperature, preventing theproducts of combustion from coming into contact with the articles iu thezones of lower temperature and permitting said articles to come intocontact with the said products of combustion during their passagethrough the hottest Zone, and finally withdrawing said articles from thehottestzone, and plunging them into a cooling-bath, substantially asdescribed.

In testimony whereof 1 have signed my name to this specification in thepresence of two subscribingwitnesses.

HENRY D. HIBBARD.

Witnesses:

ALLAN K. ALEXANDER, HUBERT HowsoN.

